This application is based upon and claims priority to German Patent Application 199 63 140.9 filed Dec. 24, 1999, which application is herein expressly incorporated by reference.
The invention relates to an intermediate bearing for a driveline of a motor vehicle, especially a commercial vehicle.
The driveline that extends from a gearbox positioned in front to the axle differential to drive the wheels of a commercial vehicle is normally of a multi-component nature with portions of universal-jointed shafts. This means that an intermediate bearing is required.
DE 37 01 887 A1 describes an intermediate bearing for a driveline. The intermediate bearing includes a housing where a resilient bearing member is accommodated in a form-fitting way. The bearing member encloses a supporting ring. A rolling contact bearing is arranged in the supporting ring to support the associated driveshaft portions. The bearing member has circumferentially distributed apertures which serve to receive filler members. By inserting the filler members, it is possible to adapt the stiffness and damping properties of the intermediate bearing to different applications. The disadvantage of this design is that such adaptation is complicated and expensive.
U.S. Pat. No. 3,325,230 describes an intermediate bearing with an outer housing, an inner housing and a rubber element arranged therebetween. The outer housing is either in one part in the form of a casting or it is of a U-shaped first plate metal part and a strip-shaped second plate metal part. The two parts are firmly connected to one another by spot welding. The inner housing includes segments and serves to accommodate the outer race of a rolling contact bearing. The individual segments have flange-like radially inwardly extending lips that axially hold the outer race of the rolling contact bearing. The outer bearing race can be fitted by moving the segments radially outwardly. The rubber element or the rubber element portions supporting the respective cup is/are radially pre-tensioned. Thus, the outer bearing race, with its outer diameter, is able to pass the region of the inwardly directed flange-like lips. In the fitted condition, it is possible not to provide any pre-tension at all. However, a pre-tension is preferably provided such that the outer race does not rotate if the shaft received in the inner bearing race rotates. The objective is to avoid any mating rust.
It is an object of the present invention to propose an intermediate bearing which can easily be adapted to different damping requirements.
In accordance with the invention, an intermediate bearing includes a housing. The housing has a stirrup-shaped cross-section. The housing has a fixing face with two straight portions and a first arched portion connecting the two straight portions. A resilient bearing member extends between a supporting ring enclosed by the resilient bearing member and the fixing face. The resilient bearing member is a rubber-like material. A locking element bridges the space between the two straight portions. The locking element includes a supporting face adapted to the opposed outer face portion of the bearing member. The supporting ring has a bore to receive a rolling contact bearing. The bore defines a longitudinal axis. The locking element is adjustable to set the pretension of the bearing member towards the longitudinal axis. The bearing member, in the pretension-free condition, is at least partially connected by adhesion to the fixing face of the housing, the supporting face of the locking element and to the supporting ring.
An advantage of this embodiment is that the required characteristics can be achieved merely by determining the respective dimension of the compression of the bearing member. The adhesion connection prevents any movement between the bearing member and the housing on the one hand and the supporting ring on the other. A further advantage is that no wear occurs in the contact regions. Damping effects are generated in the bearing member only and not in the region of contact. Longer axial paths to be accommodated by the bearing member can be permitted. Furthermore, assembly in the vehicle is facilitated because the parts are firmly associated with one another. Such firm association also means that, in the case of misalignments in the vehicle, no influence is exerted on the way in which the components are held and function. It is possible to produce an axially soft bearing.
According to a further embodiment of the invention, the bearing member is connected to the supporting ring by individual supporting portions. The supporting portions are distributed around the longitudinal axis. The load is preferably distributed onto a plurality of supporting portions in the main direction of load application.
In order to achieve a progressive characteristic curve of the bearing member with respect to damping in the radial direction, the bearing member is connected by supporting portions, distributed around the longitudinal axis, to the supporting ring and to the housing. The design selected for this purpose is such that the gap relative to the buffers is greater prior to the assembly of the driveshaft than after the assembly of the driveshaft. The weight of the driveshaft reduces the gap in the direction of load application. The change in position caused by the weight is taken into account. Thus, in the mounted condition of the driveshaft, all buffers are positioned at the same distance from the outer face of the supporting ring.
To facilitate the compression of the bearing member, the locking element is held between the two straight portions of the fixing face. The locking element can be fixed at the housing in a position which corresponds to the selected pre-tension. This can be achieved by low-heat welding methods for example, laser welding. A simple possibility to achieve the pre-tension exists if, for each straight portion, the housing is provided with an angled flange portion and if the locking element includes holding portions, which extend parallel to the flange portions, with the flange portions covering the holding portions. Both are arranged with a gap therebetween as long as the intermediate bearing is in the pre-tension-free condition. The gap between the holding portion and the flange portion is designed to accommodate the greatest possible pre-tension. Thus, the flange portions and the holding portions may come into contact with one another and may be connected to one another.
For other applications which require less pre-tension, it is possible to insert intermediate layers. As an alternative to a welded connection, it is also possible to use a connection where the corresponding through-bores, provided in the flange portions and in the holding portions which also applies to cases where intermediate layers are used, are passed through by hollow-rivet-like sleeves. The ends of the sleeves are deformed in a collar-like way and press the parts together. The through-bore which is then still in existence can be used to bolt the intermediate bearing by bolts against a transverse bar or holding blocks at the vehicle.
An adhesive may be provided to connect the bearing member to the locking element and to the housing. Alternatively, it is possible, when forming the rubber bearing member, to insert the housing and the locking member into the mold. The rubber is then injected into the mold to connect the housing and locking member to the bearing member by vulcanization when vulcanizing the bearing member.
Pre-tensioning the bearing member is simplified if the two straight portions diverge, starting from the arched portion. The arched portion, in cooperation with the straight portions, ensures that even in those bearing member regions which are remote from the locking element the required pre-tension is achieved. The pre-tension is preferably calculated such that for the highest load occurring in a particular application, all supporting portions of the bearing member, which are connected to the supporting ring are largely tensile-stress-free. Ideally, internal compressive stresses in the bearing member only exist in order to prevent, as a result of the bearing member being connected to the locking elements or the housing, tensile forces that occur to the extent that they destroy the connection between the parts and the bearing member.
From the following detailed description, taken in conjunction with the drawings and subjoined claims, other objects and advantages of the present invention will become apparent to those skilled in the art.